Gas-operated, spring-rotated, automatic choke device for shotguns



dct. 21;'195s H. E. METZ GAS-OPERATED, SPRING-ROTATED, AUTOMATIC CHOKE DEVICE FOR SHOTGUNS Filed June 16, 1955 BY W 4 ATTORNEY 2,856,719 GAS-OPERATED, SPRING-RGTATED, AUTOMATIC CHOKE DEVICE FDR SHOTGUNS Haskell E. Metz, Marion, Ohio Application June .16, 1955, Serial'No. 515,899

1 Claim; (Ci; 42-79) This invention relates to choking'devices for shotguns, and has particular reference to adjustable choke devices which may be automatically adjusted in response tofiring of the gun.-

A general object'o'f the invention is to provide anew and improved adjustable gun choke wherein a torsion-type spring is utilized for supplying the torque energy necessary for :automatically rotating a barrel-carried sleeve employed in constricting a barrel muzzle.

Another object'is to provide such'a-rotatable sleeve of a gun choke with a resiliently movable latching element havinga free end engaged normally with an adjoining stationary part of the gun barrel, whereby to preclude accidental'choke-producing rotation of the sleeve.

Still another object is to provide a gun'barrelwith-a restricted transverse por-t through which gases under pressure, developed by the firing of the gun, are caused to pass into pressure contact with a pressure-yieldable latching elemen-t,-whereby to actuate the latter in amanner removing the same from latching engagement with the 'barrel, thereby enabling the released sleeve to rotate under torque of Fig. 1.

. efiort supplied thereto by an associated torsion spring in Again, another objectis to so construct such an 'automatic choke as to enable the same, when desired, to be manually operated as anon-automatic but variablechoke means.

These and other objects and advantages present in the construction will be more fully understood from a consideration-of the following specification and annexed claim.

In the accompanying drawing:

- Fig; 1 is .a vertical longitudinal sectional view taken through the outer endof a shotgun barrel and disclosing the improved choke device of the present invention in its operative position thereon prior to the firing of a first shot;

Fig. 2 is a top plan view of the device in the position of Fig. 1;

Fig." 3 is a transverse sectional vertical view.-taken through the device on the line 3- 3 of Fig. 1;

Fig. 4 is a similar'view on the line'4-4 ofFig. 1;

Fig. 5 is a view partly in horizontal cross section and partly top plan disclosing the torsion spring-actuated sleeve of the choke device in its position producing full barrel choke following the firing of the first shot;

Fig. 6 is an end elevational view of the choke device and constrictable gun barrel extension, as indicated by the line 6-6 of Fig. 5;

In the'specific form of my improved choke device'as it appears in the embodiment thereof illustrated in the above figures of the drawings, the outer or discharge end of a shotgun barrel is idicated at 10. The barrel includes the usual cylindrical bore 11 having a fixed or constant diameter, the extreme outer end portion of the barrel being externally threaded, as at 12. Engaged With'these'threads are those provided on the wall of an internally threaded counterbore 13 of a tubular barrel extension 1'4of the improved choke device forming the present invention. The extension is formed with a bore 15 constituting nor- .mally a correspondingly diametered continuation of the barrel bore 11. The counterbore 13 ends'inwardly of the extension in an annular shoulder 16,.Which is maintained in any suitable mannerduring use of the choke de vice in firm seatingengagement with the outer circular endo'f the barrel 10.

The outer or muzzle end of the extension is provided with a plurality of circumferentially spaced longitudinally extending slits or slots 17. These slits 'or slots extend transversely through the tubular wall "of the extension, and are disposed longitudinally between the extreme outer end of the barrel attachment and positions midway of the length thereof. The'slits or slots form between them resiliently yieldable fingers '18 which,when' normally positioned, cause the bore15 to possessthroughout 'its length substantially thesame diameter as the barrel bore 11, and when forcedtogether 'to'so constrict the muzzle end of the attachmentias to produce achoke pattern on the part of shot fired therethrough.

The extreme outer ends of the fingers "18 of the extension 14 are outwardly beveled as at 19 for coacti'on with inwardly disposed beveled surfaces 20 of theouter section 21 of a choke sleeve assembly 22. The section '21 is internally threaded toward its inner end,"as a-t 23 for engagement with external complementalthreads formed intermediately of the extension 14. The sleev'e'assemb'ly includes an inner section 25 which is counterbored at 26 to receive the correspondingly formed inner end of the outer section 21. A screw 24, or other equivalent means, may be used to hold the sections 21 and 25 in rigid assembled relationship. In fact, the sections 21 and 25 may; if desired, be formed as a single, integral part, but, for reasons of facility in adjustment, as Will laterappear, it is advantageous to employ the two-part formation, as here disclosed.

Fixed on the gun barrel 10 at a position spaced inwardly from the sleeve assembly is a split, spring-anchoring, adjustable collar 26. This collar is composed of two semicircular parts which are adapted to be clamped about the barrel to retain the collar in an adjus-tably'fixed position thereon, bolts 27, or their equivalents, being employed ordinarily in effecting such clamping, One of these collar parts is formed to include adjacenttto its periphery a longitudinal opening in which is received the longitudinally directed terminal 27a of a torsion spring 27b, here shown as being of the coiled wire type. This spring is disposed coaxially with the barrel between the inner end of the sleeve section 25 and the collar 26. The opposite terminal 28 of the spring is positioned in a longitudinal'opening formed therefor in the inner sleeve section 25, as shown in Fig. 1.

muzzle, thus restricting the diameter of the bore 15. To

retain the spring 27 under such tension while the surfaces 19 and 20 are relatively disposed to allow the fingers 18 to expand to open bore positions, as shown in Fig. 1,- use is made of a latch means. i ii Q Such means in the construction illustrated, comprises a longitudinally extending spring bar. 28 The outer end of this bar is fastened as at 29 to the innersectio'n 25. of the sleeve assembly, while the inner end of said bar jis slotted at 30 to receive a catch stud31 projecting outr wardly and radially from a second or inner split collar 32 stationarily mounted on the barrel adjacent the outer collar 26. The extreme inner end of the bar 28 is formed with an inturnedlip 33 which is received in an annular groove 34 formed inthe peripheral surface of the collar 32. i This recess is of sufiicient width to receive the lip 33 in any longitudinally adjusted position of the sleeve sections. A restricted radial port or passage 34a is formed, in the gun barrel 10 and the collar 32 in longitudinal alignment with the stud 31 and at a position in transverse registry with the outer resilient and free end portion of thebar 28 when the 18.11161 is engaged withthe stud 31.

In the use ofjmy improved automatic choke attachment, the parts are positioned on the outer end of the gun barrel 10, as shown in Fig. 1. When so positioned the sleeveassernbly will have been rotated in an anticlockwise direction, when looking toward the muzzle end of the gun barrel, and the collar 26 rotated in a clockwise directionand clamped therein, as in Fig. 6, in order to place the spring 27 under tension in developing torque forces capable-of rotating the sleeve assembly in a clockwise direction. To hold the spring under such tension, and to maintain the beveled surfaces 19 and in open bore relation,fthe resilient latch bar has the slot 30 thereof disposed to receive the outwardly. projecting stud 31 of the stationary collar'32.

With theparts of the attachment thus positioned, and as illustrated in Fig. 1, the firing of a first shot, because or unch oked bore diameten will produce a normal relatively wide. pattern of the scattering shot. -As a result of gas pressures developed in the gun barrel from the initially fired shot, a part. ofsuch pressure will pass into and through the port or passage 34a, this action taking place with sufiicient force to flex the inner end of the latch bar 28 upwardly and releasing the same from engagement with the stud 31. Such release of the latch bar enables the tensioned coil spring 27 to respond at once and supply torque to rotate. the sleeve assembly on the threads 24 of the barrel extensionina direction causing the sleeve assembly to move inwardly and longitudinally of the barrel to the position shown in Fig. 5. In this position, the beveled surface 20 moves. inwardly over the cooperatively beveled surfaces 19 to flex the fingers 18 radially inwardly to muzzle-constricting positions, so that when a second shot is fired, the shot pattern produced thereby will be more concentrated than that of. the first shot, Iwhereby to compensate for the greater distance between the gun and receding targets.

While I am aware that the prior art proposes the employment of automatically operating choke devicesfor shotguns in which muzzle constriction is produced by recoil and/or gas pressures developed as a result of the firing of an initial shot, yet, none of these prior proposals has found commercial acceptance, since only conventional manually operated types of chokes are now in practical use. This condition is believed to beattributable to the unreliability of the mechanisms used in the prior automatic types of devices and their general inefiectiveness for intended purposes. Thus, it has been proposed to rotate the choke sleeves by the impingement of shot-developed pressure gases on angular blade surfaces formed on the outer ends of the sleeves. Again, it has been proposed to slide the sleeves longitudinally on the barrel extensions by the use of trigger-released springs. Greater reliability and more positive operation, however, is obtained with the 'use of the torsion spring of the present invention over these prior proposals, particularly through the high torque effect which such a torsion spring produces on an associated thread-carried sleeve, whereby to cause said sleeve to move positively and effectively in contracting the resilient choke fingers of the barrel extension. Moreover, the simplicity and low cost of the present construction is another important factor in its favor.

The outer and inner sections 21 and 25, respectively, of the sleeve assembly provide for the relative adjustment thereof in a manner maintaining the effective bore diameter of the gun barrel extension best a'dapted to the liking of different gun users, and such adjustments may be maintained by the employment of the screw 24. Also, the barrel extension may be turned manually, instead of automatically, if desired, by loosening the adjustable collar 26 and thereby removing spring tension.

While I have set forth and described in detail a single preferred embodiment of the automatic gun choke forming the present invention, it will be understood that this embodiment is but an illustrative or exemplary one," and, therefore, the construction thereof is subject to certain variationor modification falling within the scope of the appended claim.

I claim; i a p In combination with a. shotgun having a barrel; a radially, resiliently constrictible muzzle extension attached to the muzzle end of said barrel and forming a longitudinal continuation thereof and operable'to vary the pattern of shot fired therethrough; a sleeve member threadedly carried on said muzzle extension and operable upon rotation in one direction to constrict said extension; a torsion spring. positioned around the barrel of the shotgun adjacent said sleeve member and having an end thereof connected directly with said sleeve member; means stationarily securing an opposite end of said spring to the barrel of said shotgun, said spring beingarranged to urge saidsleeve member to rotate in said one direction to constrict said muzzle extension; a resiliently flexible latch arm carried for rotation with said sleeve member and extending longitudinally inwardly of the barrel of said shotgun over and beyond saidspring; catch means sta tionarily mounted on the barrel of the shotgun rearwardly of said spring and engageable with said latch arm to'hold said sleeve member against muzzle-constricting rotation andsaid spring undertension; and means, comprising a gas passage extending radially through the barrel of said shotgun and in longitudinal alignment with said catch means, operable in response to the firing of the shotgun to disengage said latcharm from said catch means and thereby cause said sleeve member to rotate in said one direction under influence of said torsion spring.

References Cited in the file of this patent UNITED STATES PATENTS 2,134,238 Sedberry Q Oct. 25, 1938 2,453,747 Egleson Nov. 16, 1948 2,759,286 Moore Aug. 21, 1956 2,765,564 Schroeder Oct. 9, 1956 

